This is the "OnInputProcessing" section in the Event Handler of the same HTML page in the BSP.
data: date1_low TYPE ZWB_TS_DATETIME,
date1_high TYPE ZWB_TS_DATETIME,
form_date_low TYPE c,
form_date_high TYPE c,
date_low TYPE dats,
date_high TYPE dats.
case event_id.
when 'submit'.
form_date_low = request->get_form_field('input_date1_low').
form_date_high = request->get_form_field('input_date1_high').
date_low = form_date_low.
date_high = form_date_high.
CALL FUNCTION 'Z_WB_EXT_TREK_00'
EXPORTING
date_low = w_date_low.
date_high = w_date_high.
endcase.